והיה כצאת משה אל האהל יקומו כל העם ונצבו איש פתח אהלו
Midrash Tanchuma derives from here that one must stand up and show respect to an old man, a scholar, Av Bais Din; Head of the Rabbinical Court, and a king. He must remain at attention until the individual whom he is honoring walks out of sight. One Tanna adds that as a result of this halachah, if one of these individuals would notice a large group of people near his intended walking path, he should alter his route, so not to disturb them, since they would have to stop whatever they were doing in order to show him respect. A…